Electrostatic spraying apparatus with repelling electrode means and gas shroud

Abstract

Electrostatic spraying apparatus comprising a housing having an opening, liquid atomization means and induction charging electrode means mounted in said housing to deliver an electrically charged spray of liquid particles outwardly through the opening, inlet means to said housing for delivering to the housing a flow of gas for subsequent envelopment of the electrically charged spray of liquid particles upon exit from the housing, and repelling electrode means of a polarity the same as the electrically charged spray and defining an electrical repulsion zone for repelling said spray immediately prior to and after the exiting of said spray from the opening. Relatedly disclosed are an electrostatic induction charging gas shroud adapter and a repelling electrode adapter, each to be employed with appropriate atomization means to deliver an electrically charged spray of liquid particles as described above.

What is claimed is: 
     
       1. Electrostatic spraying apparatus comprising: (a) an electrically non-conductive or dielectric housing having an opening with a perimeter;   (b) liquid atomization means mounted in said housing, said liquid atomization means being capable of dispersing a liquid into a spray of liquid particles directed outwardly through said opening of said housing;   (c) a screen extending essentially radially outwardly from said liquid atomization means and disposed substantially entirely between said liquid atomization means and said perimeter of said opening, said screen adjacent said liquid atomization means providing induction charging electrode means and the remainder of said screen being dielectric or electrically non-conductive, said induction charging electrode means being chargeable to a first polarity and being in cooperative spatial relationship with said liquid atomization means to impart an electrical charge on said liquid particles substantially simultaneously with the formation of said liquid particles to produce an electrically charged spray of liquid particles, said imparted electrical charge being of a second polarity which is opposite the polarity of said induction charging electrode means;   (d) gas inlet means to said housing for delivering a flow of gas to said housing whereby said gas exits through said opening of said housing and substantially concentrically envelops said electrically charged spray of liquid particles; and   (e) repelling electrode means mounted within said housing and spaced inwardly from said perimeter of said opening, said repelling electrode means being substantially electrically isolated from said induction charging electrode means and being chargeable to a polarity opposite the polarity of said induction charging electrode means and of the same polarity as said electrically charged spray of liquid particles to repel said electrically charged spray of liquid particles immediately prior to the exiting of said electrically charged spray of liquid from said opening.   
     
     
       2. Electrostatic spraying apparatus as claimed in claim 1 wherein said induction charging electrode means comprises a semi-conductive film coating. 
     
     
       3. Electrostatic spraying apparatus as claimed in claim 2 wherein said screen is constructed of nylon. 
     
     
       4. Electrostatic spraying apparatus as claimed in claim 2 wherein said induction charging electrode means is a film coating of a polyurethane resin-graphite matrix. 
     
     
       5. Electrostatic spraying apparatus as claimed in claim 1 wherein said gas exits through said screen between said induction charging electrode means and said repelling electrode means. 
     
     
       6. Electrostatic spraying apparatus as claimed in claim 1 wherein said repelling electrode means is a film coating of a polyurethane resin-graphite matrix. 
     
     
       7. Electrostatic spraying apparatus as claimed in claim 1 wherein said housing is constructed of fiberglass impregnated with epoxy resin. 
     
     
       8. Electrostatic spraying apparatus as claimed in claim 1 wherein said liquid atomization means is an air-atomization spray gun. 
     
     
       9. Electrostatic spraying apparatus as claimed in claim 1 wherein said gas inlet means is a tubular opening extending from said housing. 
     
     
       10. Electrostatic induction charging gas shroud adapter comprising: (a) an electrically non-conductive or dielectric housing to which can be mounted liquid atomization means, said housing having an opening with a perimeter, said liquid atomization means when mounted being capable of dispersing a liquid into a spray of liquid particles directed outwardly through said opening of said housing;   (b) a screen extending essentially radially outwardly from said liquid atomization means when mounted and disposed substantially entirely between said liquid atomization means when mounted and said perimeter of said opening, said screen adjacent said liquid atomization means when mounted providing induction charging electrode means and the remainder of said screen being dielectric or electrically non-conductive, said induction charging electrode means being chargeable to a first polarity and being in cooperative spatial relationship with said liquid atomization means when mounted to impart an electrical charge on said liquid particles substantially simultaneously with the formation of said liquid particles to produce an electrically charged spray of liquid particles, said imparted electrical charge being of a second polarity which is opposite the polarity of said induction charging electrode means;   (c) gas inlet means to said housing for delivering a flow of gas to said housing whereby said gas exits through said opening of said housing and substantially concentrically envelops said electrically charged spray of liquid particles; and   (d) repelling electrode means mounted within said housing and spaced inwardly from said perimeter of said opening, said repelling electrode means being substantially electrically isolated from said induction charging electrode means and being charageable to a polarity opposite the polarity of said induction charging electrode means and of the same polarity as said electrically charged spray of liquid particles to repel said electrically charged spray of liquid particles immediately prior to the exiting of said electrically charged spray of liquid particles from said opening.   
     
     
       11. Electrostatic induction charging adapter as claimed in claim 10 wherein said induction charging electrode means comprises a semiconductive film coating. 
     
     
       12. Electrostatic induction charging adapter as claimed in claim 11 wherein said screen is constructed of nylon. 
     
     
       13. Electrostatic induction charging adapter as claimed in claim 11 wherein said induction charging electrode means is a film coating of a polyurethane resin-graphite matrix. 
     
     
       14. Electrostatic induction charging adapter as claimed in claim 10 wherein said gas exits through said screen between said induction charging electrode means and said repelling electrode means. 
     
     
       15. Electrostatic induction charging adapter as claimed in claim 10 wherein said repelling electrode means is a film coating of a polyurethane resin-graphite matrix. 
     
     
       16. Electrostatic induction charging adapter as claimed in claim 10 wherein said housing is constructed of fiberglass impregnated with epoxy resin. 
     
     
       17. Electrostatic induction charging adapter as claimed in claim 10 wherein said gas inlet means is a tubular opening extending from said housing. 
     
     
       18. Repelling electrode adapter for induction charging electrostatic spraying apparatus having induction charging electrode means chargeable to a first polarity, said adapter comprising: (a) an electrically non-conductive or dielectric housing mountable to an induction charging electrostatic liquid atomization means, said housing having an opening with a perimeter; and   (b) semi-conductive repelling electrode means disposed in said housing and spaced inwardly from said perimeter of said opening, said semi-conductive repelling electrode means being substantially electrically isolated from said induction charging electrode means when mounted and being chargeable to a polarity opposite the polarity of said induction charging electrode means to define when mounted an electrical repulsion zone for repelling an inductively charged spray of liquid particles issuing from said induction charging electrostatic spraying apparatus.   
     
     
       19. Repelling electrode adapter as claimed in claim 18 wherein said electrode means is a film coating of a polyurethane resin-graphite matrix. 
     
     
       20. Repelling electrode adapter as claimed in claim 18 wherein said housing is constructed of fiberglass impregnated with epoxy resin.